Conventionally, there has been known a Remote Equivalent Copy method (REC) as a function of protecting data from disasters, terrorism attacks, and the like and quickly restoring data. The REC is, specifically, a function of copying data stored in a storage apparatus to another storage apparatus installed in a remote site.
Meanwhile, the storage apparatus controls the sequence in which data is written to a disk in such a manner that even if writing to the disk suddenly stops, for example, due to a crash of the sever OS (Operating System), data may be restored to its original state. Such a writing sequence control is also performed in a storage apparatus of a copy destination (hereinafter referred to simply as a “copy destination”) in the same manner when the REC is performed. For this reason, in order for the copy destination to restore data received from a storage apparatus of a copy source (hereinafter referred to simply as a “copy source”) to the same state as that of the copy source, the sequence (transfer sequence) in which data is copied from the copy source to the copy destination is requested to be the same as the sequence in which data is written to the copy source.
As the method of guaranteeing the sequence in which data is written to a copy destination, there is a method by which copy data to be transferred to the copy destination is temporarily stored in a buffer and the data in the buffer is collectively transferred to the copy destination in a predetermined timing.
There is Japanese Laid-Open Patent Publication No. 2006-260292 as a reference document.